This invention is directed to a bipolar crossed-field switch tube and circuit for particular use in circuits where conduction in either direction is desired.
Bipolar conduction capability in a crossed-field switch tube and offswitching in either conduction direction is essential for all AC applications of the switch tube. Furthermore, it is desirable also for DC breaker applications since, in multi-terminal transmission systems, reversal of power flow is achieved most conveniently by reversal of the current flow direction.
Crossed magnetic and electric field devices are known in the prior art. Perhaps the first disclosure of a crossed-field device for switching is Penning Pat. No. 2,182,736. Boucher Pat. Nos. 3,215,893 and 3,215,939 are primarily directed to crossed-field rectifier type switching and are directed to an improvement where the shape of the magnetic field is asserted to improve rectifying action by providing a lower breakdown voltage in one direction than the other between the two electrodes which define the gas-filled space.
M. A. Lutz and R. C. Knechtli Pat. No. 3,838,061 is one of a series of patents which indicates modern developments for higher voltage off switching and higher current capability. Other patents of this nature include G. A. G. Hofmann Pat. No. 3,604,977 and G. A. G. Hofmann and R. C. Knechtli Pat. No. 3,558,960. There are also other patents directed to improvements in the crossed-field switching device.
One particular patent which is pertinent background for the present invention is G. A. G. Hofmann and R. E. Lund Pat. No. 3,641,384 which described a crossed-field switching device which has three spaced electrodes and two gas-filled annular spaces therebetween. That patent represents a structure which was for the purpose of higher voltage hold-off in series connection and higher current capacity in parallel connection in DC applications. In other words, it was intended that both gaps would be conducting and off-switching at the same time.